Low deck versions but you can see they are the same intake. Bolt holes would need filled on the 4150 before you re drilled for a 4500 as they slightly overlap. I backed to backed these on my 512, the 4150 with a 4500 adaptor was slightly faster and had better distribution. I did run a 2” spacer on the 4500 as well to even the plenum volume. I’ve also been told by numerous people the 4150 works better before I even tried it.